| //===--- CGCXX.cpp - Emit LLVM Code for declarations ----------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This contains code dealing with C++ code generation. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| // We might split this into multiple files if it gets too unwieldy |
| |
| #include "CGCXXABI.h" |
| #include "CodeGenFunction.h" |
| #include "CodeGenModule.h" |
| #include "clang/AST/ASTContext.h" |
| #include "clang/AST/RecordLayout.h" |
| #include "clang/AST/Decl.h" |
| #include "clang/AST/DeclCXX.h" |
| #include "clang/AST/DeclObjC.h" |
| #include "clang/AST/Mangle.h" |
| #include "clang/AST/StmtCXX.h" |
| #include "clang/Frontend/CodeGenOptions.h" |
| #include "llvm/ADT/StringExtras.h" |
| using namespace clang; |
| using namespace CodeGen; |
| |
| /// Determines whether the given function has a trivial body that does |
| /// not require any specific codegen. |
| static bool HasTrivialBody(const FunctionDecl *FD) { |
| Stmt *S = FD->getBody(); |
| if (!S) |
| return true; |
| if (isa<CompoundStmt>(S) && cast<CompoundStmt>(S)->body_empty()) |
| return true; |
| return false; |
| } |
| |
| /// Try to emit a base destructor as an alias to its primary |
| /// base-class destructor. |
| bool CodeGenModule::TryEmitBaseDestructorAsAlias(const CXXDestructorDecl *D) { |
| if (!getCodeGenOpts().CXXCtorDtorAliases) |
| return true; |
| |
| // If the destructor doesn't have a trivial body, we have to emit it |
| // separately. |
| if (!HasTrivialBody(D)) |
| return true; |
| |
| const CXXRecordDecl *Class = D->getParent(); |
| |
| // If we need to manipulate a VTT parameter, give up. |
| if (Class->getNumVBases()) { |
| // Extra Credit: passing extra parameters is perfectly safe |
| // in many calling conventions, so only bail out if the ctor's |
| // calling convention is nonstandard. |
| return true; |
| } |
| |
| // If any field has a non-trivial destructor, we have to emit the |
| // destructor separately. |
| for (CXXRecordDecl::field_iterator I = Class->field_begin(), |
| E = Class->field_end(); I != E; ++I) |
| if ((*I)->getType().isDestructedType()) |
| return true; |
| |
| // Try to find a unique base class with a non-trivial destructor. |
| const CXXRecordDecl *UniqueBase = 0; |
| for (CXXRecordDecl::base_class_const_iterator I = Class->bases_begin(), |
| E = Class->bases_end(); I != E; ++I) { |
| |
| // We're in the base destructor, so skip virtual bases. |
| if (I->isVirtual()) continue; |
| |
| // Skip base classes with trivial destructors. |
| const CXXRecordDecl *Base |
| = cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| if (Base->hasTrivialDestructor()) continue; |
| |
| // If we've already found a base class with a non-trivial |
| // destructor, give up. |
| if (UniqueBase) return true; |
| UniqueBase = Base; |
| } |
| |
| // If we didn't find any bases with a non-trivial destructor, then |
| // the base destructor is actually effectively trivial, which can |
| // happen if it was needlessly user-defined or if there are virtual |
| // bases with non-trivial destructors. |
| if (!UniqueBase) |
| return true; |
| |
| /// If we don't have a definition for the destructor yet, don't |
| /// emit. We can't emit aliases to declarations; that's just not |
| /// how aliases work. |
| const CXXDestructorDecl *BaseD = UniqueBase->getDestructor(); |
| if (!BaseD->isImplicit() && !BaseD->hasBody()) |
| return true; |
| |
| // If the base is at a non-zero offset, give up. |
| const ASTRecordLayout &ClassLayout = Context.getASTRecordLayout(Class); |
| if (ClassLayout.getBaseClassOffsetInBits(UniqueBase) != 0) |
| return true; |
| |
| return TryEmitDefinitionAsAlias(GlobalDecl(D, Dtor_Base), |
| GlobalDecl(BaseD, Dtor_Base)); |
| } |
| |
| /// Try to emit a definition as a global alias for another definition. |
| bool CodeGenModule::TryEmitDefinitionAsAlias(GlobalDecl AliasDecl, |
| GlobalDecl TargetDecl) { |
| if (!getCodeGenOpts().CXXCtorDtorAliases) |
| return true; |
| |
| // The alias will use the linkage of the referrent. If we can't |
| // support aliases with that linkage, fail. |
| llvm::GlobalValue::LinkageTypes Linkage |
| = getFunctionLinkage(cast<FunctionDecl>(AliasDecl.getDecl())); |
| |
| switch (Linkage) { |
| // We can definitely emit aliases to definitions with external linkage. |
| case llvm::GlobalValue::ExternalLinkage: |
| case llvm::GlobalValue::ExternalWeakLinkage: |
| break; |
| |
| // Same with local linkage. |
| case llvm::GlobalValue::InternalLinkage: |
| case llvm::GlobalValue::PrivateLinkage: |
| case llvm::GlobalValue::LinkerPrivateLinkage: |
| break; |
| |
| // We should try to support linkonce linkages. |
| case llvm::GlobalValue::LinkOnceAnyLinkage: |
| case llvm::GlobalValue::LinkOnceODRLinkage: |
| return true; |
| |
| // Other linkages will probably never be supported. |
| default: |
| return true; |
| } |
| |
| llvm::GlobalValue::LinkageTypes TargetLinkage |
| = getFunctionLinkage(cast<FunctionDecl>(TargetDecl.getDecl())); |
| |
| if (llvm::GlobalValue::isWeakForLinker(TargetLinkage)) |
| return true; |
| |
| // Derive the type for the alias. |
| const llvm::PointerType *AliasType |
| = getTypes().GetFunctionType(AliasDecl)->getPointerTo(); |
| |
| // Find the referrent. Some aliases might require a bitcast, in |
| // which case the caller is responsible for ensuring the soundness |
| // of these semantics. |
| llvm::GlobalValue *Ref = cast<llvm::GlobalValue>(GetAddrOfGlobal(TargetDecl)); |
| llvm::Constant *Aliasee = Ref; |
| if (Ref->getType() != AliasType) |
| Aliasee = llvm::ConstantExpr::getBitCast(Ref, AliasType); |
| |
| // Create the alias with no name. |
| llvm::GlobalAlias *Alias = |
| new llvm::GlobalAlias(AliasType, Linkage, "", Aliasee, &getModule()); |
| |
| // Switch any previous uses to the alias. |
| llvm::StringRef MangledName = getMangledName(AliasDecl); |
| llvm::GlobalValue *Entry = GetGlobalValue(MangledName); |
| if (Entry) { |
| assert(Entry->isDeclaration() && "definition already exists for alias"); |
| assert(Entry->getType() == AliasType && |
| "declaration exists with different type"); |
| Alias->takeName(Entry); |
| Entry->replaceAllUsesWith(Alias); |
| Entry->eraseFromParent(); |
| } else { |
| Alias->setName(MangledName); |
| } |
| |
| // Finally, set up the alias with its proper name and attributes. |
| SetCommonAttributes(cast<NamedDecl>(AliasDecl.getDecl()), Alias); |
| |
| return false; |
| } |
| |
| void CodeGenModule::EmitCXXConstructors(const CXXConstructorDecl *D) { |
| // The constructor used for constructing this as a complete class; |
| // constucts the virtual bases, then calls the base constructor. |
| EmitGlobal(GlobalDecl(D, Ctor_Complete)); |
| |
| // The constructor used for constructing this as a base class; |
| // ignores virtual bases. |
| EmitGlobal(GlobalDecl(D, Ctor_Base)); |
| } |
| |
| void CodeGenModule::EmitCXXConstructor(const CXXConstructorDecl *D, |
| CXXCtorType Type) { |
| // The complete constructor is equivalent to the base constructor |
| // for classes with no virtual bases. Try to emit it as an alias. |
| if (Type == Ctor_Complete && |
| !D->getParent()->getNumVBases() && |
| !TryEmitDefinitionAsAlias(GlobalDecl(D, Ctor_Complete), |
| GlobalDecl(D, Ctor_Base))) |
| return; |
| |
| const CGFunctionInfo &FnInfo = getTypes().getFunctionInfo(D, Type); |
| |
| // FIXME: re-use FnInfo in this computation! |
| llvm::Function *Fn = cast<llvm::Function>(GetAddrOfCXXConstructor(D, Type)); |
| setFunctionLinkage(D, Fn); |
| |
| CodeGenFunction(*this).GenerateCode(GlobalDecl(D, Type), Fn, FnInfo); |
| |
| SetFunctionDefinitionAttributes(D, Fn); |
| SetLLVMFunctionAttributesForDefinition(D, Fn); |
| } |
| |
| llvm::GlobalValue * |
| CodeGenModule::GetAddrOfCXXConstructor(const CXXConstructorDecl *D, |
| CXXCtorType Type) { |
| GlobalDecl GD(D, Type); |
| |
| llvm::StringRef Name = getMangledName(GD); |
| if (llvm::GlobalValue *V = GetGlobalValue(Name)) |
| return V; |
| |
| const FunctionProtoType *FPT = D->getType()->getAs<FunctionProtoType>(); |
| const llvm::FunctionType *FTy = |
| getTypes().GetFunctionType(getTypes().getFunctionInfo(D, Type), |
| FPT->isVariadic()); |
| return cast<llvm::Function>(GetOrCreateLLVMFunction(Name, FTy, GD, |
| /*ForVTable=*/false)); |
| } |
| |
| void CodeGenModule::EmitCXXDestructors(const CXXDestructorDecl *D) { |
| // The destructor in a virtual table is always a 'deleting' |
| // destructor, which calls the complete destructor and then uses the |
| // appropriate operator delete. |
| if (D->isVirtual()) |
| EmitGlobal(GlobalDecl(D, Dtor_Deleting)); |
| |
| // The destructor used for destructing this as a most-derived class; |
| // call the base destructor and then destructs any virtual bases. |
| EmitGlobal(GlobalDecl(D, Dtor_Complete)); |
| |
| // The destructor used for destructing this as a base class; ignores |
| // virtual bases. |
| EmitGlobal(GlobalDecl(D, Dtor_Base)); |
| } |
| |
| void CodeGenModule::EmitCXXDestructor(const CXXDestructorDecl *D, |
| CXXDtorType Type) { |
| // The complete destructor is equivalent to the base destructor for |
| // classes with no virtual bases, so try to emit it as an alias. |
| if (Type == Dtor_Complete && |
| !D->getParent()->getNumVBases() && |
| !TryEmitDefinitionAsAlias(GlobalDecl(D, Dtor_Complete), |
| GlobalDecl(D, Dtor_Base))) |
| return; |
| |
| // The base destructor is equivalent to the base destructor of its |
| // base class if there is exactly one non-virtual base class with a |
| // non-trivial destructor, there are no fields with a non-trivial |
| // destructor, and the body of the destructor is trivial. |
| if (Type == Dtor_Base && !TryEmitBaseDestructorAsAlias(D)) |
| return; |
| |
| const CGFunctionInfo &FnInfo = getTypes().getFunctionInfo(D, Type); |
| |
| // FIXME: re-use FnInfo in this computation! |
| llvm::Function *Fn = cast<llvm::Function>(GetAddrOfCXXDestructor(D, Type)); |
| setFunctionLinkage(D, Fn); |
| |
| CodeGenFunction(*this).GenerateCode(GlobalDecl(D, Type), Fn, FnInfo); |
| |
| SetFunctionDefinitionAttributes(D, Fn); |
| SetLLVMFunctionAttributesForDefinition(D, Fn); |
| } |
| |
| llvm::GlobalValue * |
| CodeGenModule::GetAddrOfCXXDestructor(const CXXDestructorDecl *D, |
| CXXDtorType Type) { |
| GlobalDecl GD(D, Type); |
| |
| llvm::StringRef Name = getMangledName(GD); |
| if (llvm::GlobalValue *V = GetGlobalValue(Name)) |
| return V; |
| |
| const llvm::FunctionType *FTy = |
| getTypes().GetFunctionType(getTypes().getFunctionInfo(D, Type), false); |
| |
| return cast<llvm::Function>(GetOrCreateLLVMFunction(Name, FTy, GD, |
| /*ForVTable=*/false)); |
| } |
| |
| static llvm::Value *BuildVirtualCall(CodeGenFunction &CGF, uint64_t VTableIndex, |
| llvm::Value *This, const llvm::Type *Ty) { |
| Ty = Ty->getPointerTo()->getPointerTo(); |
| |
| llvm::Value *VTable = CGF.GetVTablePtr(This, Ty); |
| llvm::Value *VFuncPtr = |
| CGF.Builder.CreateConstInBoundsGEP1_64(VTable, VTableIndex, "vfn"); |
| return CGF.Builder.CreateLoad(VFuncPtr); |
| } |
| |
| llvm::Value * |
| CodeGenFunction::BuildVirtualCall(const CXXMethodDecl *MD, llvm::Value *This, |
| const llvm::Type *Ty) { |
| MD = MD->getCanonicalDecl(); |
| uint64_t VTableIndex = CGM.getVTables().getMethodVTableIndex(MD); |
| |
| return ::BuildVirtualCall(*this, VTableIndex, This, Ty); |
| } |
| |
| /// BuildVirtualCall - This routine is to support gcc's kext ABI making |
| /// indirect call to virtual functions. It makes the call through indexing |
| /// into the vtable. |
| llvm::Value * |
| CodeGenFunction::BuildAppleKextVirtualCall(const CXXMethodDecl *MD, |
| NestedNameSpecifier *Qual, |
| const llvm::Type *Ty) { |
| llvm::Value *VTable = 0; |
| assert((Qual->getKind() == NestedNameSpecifier::TypeSpec) && |
| "BuildAppleKextVirtualCall - bad Qual kind"); |
| |
| const Type *QTy = Qual->getAsType(); |
| QualType T = QualType(QTy, 0); |
| const RecordType *RT = T->getAs<RecordType>(); |
| assert(RT && "BuildAppleKextVirtualCall - Qual type must be record"); |
| const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); |
| |
| if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) |
| return BuildAppleKextVirtualDestructorCall(DD, Dtor_Complete, RD); |
| |
| VTable = CGM.getVTables().GetAddrOfVTable(RD); |
| Ty = Ty->getPointerTo()->getPointerTo(); |
| VTable = Builder.CreateBitCast(VTable, Ty); |
| assert(VTable && "BuildVirtualCall = kext vtbl pointer is null"); |
| MD = MD->getCanonicalDecl(); |
| uint64_t VTableIndex = CGM.getVTables().getMethodVTableIndex(MD); |
| uint64_t AddressPoint = |
| CGM.getVTables().getAddressPoint(BaseSubobject(RD, 0), RD); |
| VTableIndex += AddressPoint; |
| llvm::Value *VFuncPtr = |
| Builder.CreateConstInBoundsGEP1_64(VTable, VTableIndex, "vfnkxt"); |
| return Builder.CreateLoad(VFuncPtr); |
| } |
| |
| /// BuildVirtualCall - This routine makes indirect vtable call for |
| /// call to virtual destructors. It returns 0 if it could not do it. |
| llvm::Value * |
| CodeGenFunction::BuildAppleKextVirtualDestructorCall( |
| const CXXDestructorDecl *DD, |
| CXXDtorType Type, |
| const CXXRecordDecl *RD) { |
| llvm::Value * Callee = 0; |
| const CXXMethodDecl *MD = cast<CXXMethodDecl>(DD); |
| // FIXME. Dtor_Base dtor is always direct!! |
| // It need be somehow inline expanded into the caller. |
| // -O does that. But need to support -O0 as well. |
| if (MD->isVirtual() && Type != Dtor_Base) { |
| // Compute the function type we're calling. |
| const CGFunctionInfo *FInfo = |
| &CGM.getTypes().getFunctionInfo(cast<CXXDestructorDecl>(MD), |
| Dtor_Complete); |
| const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>(); |
| const llvm::Type *Ty |
| = CGM.getTypes().GetFunctionType(*FInfo, FPT->isVariadic()); |
| |
| llvm::Value *VTable = CGM.getVTables().GetAddrOfVTable(RD); |
| Ty = Ty->getPointerTo()->getPointerTo(); |
| VTable = Builder.CreateBitCast(VTable, Ty); |
| DD = cast<CXXDestructorDecl>(DD->getCanonicalDecl()); |
| uint64_t VTableIndex = |
| CGM.getVTables().getMethodVTableIndex(GlobalDecl(DD, Type)); |
| uint64_t AddressPoint = |
| CGM.getVTables().getAddressPoint(BaseSubobject(RD, 0), RD); |
| VTableIndex += AddressPoint; |
| llvm::Value *VFuncPtr = |
| Builder.CreateConstInBoundsGEP1_64(VTable, VTableIndex, "vfnkxt"); |
| Callee = Builder.CreateLoad(VFuncPtr); |
| } |
| return Callee; |
| } |
| |
| llvm::Value * |
| CodeGenFunction::BuildVirtualCall(const CXXDestructorDecl *DD, CXXDtorType Type, |
| llvm::Value *This, const llvm::Type *Ty) { |
| DD = cast<CXXDestructorDecl>(DD->getCanonicalDecl()); |
| uint64_t VTableIndex = |
| CGM.getVTables().getMethodVTableIndex(GlobalDecl(DD, Type)); |
| |
| return ::BuildVirtualCall(*this, VTableIndex, This, Ty); |
| } |
| |